How to find out the maximum and minimum value of a function?

Which shows the image of rectangle abcd after the rotation (x, y) → (–y, x)?

An equation of the line tangent to y=x^3+3x^2+2 at its point of inflection is

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?